This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We propose to use x-ray absorption spectroscopy to characterize the metal-halogen biomaterials that are biosynthesized in the cuticular tools of most arthropods and a few other phyla. Maturation of these cuticular tools (fangs, stings, jaws, claws, etc.) involves the transport and deposition of transition metals (Mn, Fe, Cu, Zn) and halogens (Cl, Br, I) in amorphous structures that cannot be characterized by x-ray diffraction. We expect to uncover new biology, biochemistry, and materials chemistry in determining the structures and spatial distribution of these biomaterials during biosynthesis and maturation of these tools. Bulk XAS, followed by imaging and x-ray microscopy will allow detailed structural analysis. These experiments range from the straightforward (transition metal bulk XAS by fluorescence excitation) to the challenging (low-energy imaging at micron spatial resolution) that will take advantage of beamline developments for SPEAR3.